protactinium Hear it!

protactinium definition

pro·tac·tin·ium (prō′tak tin′ē əm)

noun

a rare, radioactive, metallic chemical element, one of the actinides, found in pitchblende: symbol, Pa; at. no., 91

Etymology: ModL: see proto- & actinium

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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